The Gem Mine can be unlocked in the Builder’s Base. It requires Builder’s Hall level 3 to be repaired.

The Gem Mine, as its name suggests, produces Gems. These mined Gems are then stored until the player collects them or the storage fills.

Gem Mines undergo a significant visual change at level 3.

In its initial ruined state, it appears as a derelict, overgrown cave. A Gem insignia on a wooden hexagon on the side of the rocks can be found on the Mine’s side. There are large broken wooden planks covering the entrance, and a broken box. There are also Gems scattered around the Mine.

When reconstructed, the Gem Mine is a cave-like structure with a wooden arch supported by ropes at the entrance. The Gem insignia is present on the side of the Mine, and a rail conveyor extends out of the cave, into a box containing Gems. Outside the cave is a torch.

At level 2, the Gem Mine’s arch and base is reinforced by metal.The grass on the side of the Gem Mine has disappeared.

At level 3, the top of the cave is replaced by an open roof and a pulley system. More wooden planks are added to the sides of the opened roof, in order to support the pulley. Additional reinforcing metal plates appear at the top of the entrance.

At level 4, the reinforcing metal plates change to a bronze-colored scheme. A second pulley is also added.

At level 5, the reinforcing wooden structure now extends to the back of the cave, and additional bronze plates are added to the back side of the roof.

At level 6, the pulley system becomes bronze, with wood covering the roof.

This building serves no purpose on defense, so placing it on the outside to protect your defenses can be good.

Placing it in the corner can stall your opponent from getting three stars on your base.

This building has low hitpoints, so it is better to place it outside of the walls or the base.

The Gem Mine is the only building that produces Gems.

There are no storages for the Gems except for the Gem Mine due to your unlimited Gem inventory.

Unlike the Gold Mine, there is no cart that delivers the Gems to the surface, instead, a conveyor belt delivers the Gems to the surface.

When the Gem Mine is full, the Gems are in a large, unorganized pile right outside the entrance of the Gem Mine.

Tapping this icon displays information about the Gem Mine, such as Level, Capacity, Production and Hitpoints.

Tapping this icon begins upgrading the Gem Mine to the next level, if you have enough resources and a free Master Builder. When the Gem Mine is at maximum level, this icon is not shown.

Tapping this icon, which is displayed only while an upgrade is in progress, instantly finishes that upgrade at the cost of the displayed number of Gems.

Tapping this icon, which is displayed only while an upgrade is in progress, cancels the current upgrade and refunds half of the upgrade cost.

Builder Hall Level

1

2

3

4

5

Number Available

0

0

1

1

1

Size

3×3

Level

Build Cost

Build Time

ExperienceGained

Capacity

Production Rate (per day)

Production Time per Gem

Time to Fill

Catch-up Point*

Hitpoints

Builder HallLevel Required

1

120,000

1 hr

60

10

2.1

11h 25m 43s

4d 18h 17m 9s

N/A

300

3

2

180,000

2 hr

84

11

2.4

10h

4d 14h

14h

345

3

3

240,000

6 hr

146

12

2.6

9h 13m 51s

4d 14h 46m 9s

3d

397

4

4

450,000

8 hr

169

13

2.8

8h 34m 17s

4d 15h 25m 43s

4d 8h

457

4

5

1,000,000

10 hr

189

14

3.1

7h 44m 31s

4d 12h 23m 14s

3d 21h 20m

526

5

6

1,500,000

12 hr

207

16

3.3

7h 16m 22s

4d 20h 21m 49s

7d 18h

605

6

* The Catch-Up Point is the time at which the newly upgraded Gem Mine has equaled the total production of the mine had it not been upgraded – this does not consider recovering the cost of the Builder Elixir required to perform the upgrade.

Caveat: The Catch-Up Point calculation assumes that the player collects all resources from the Gem Mine without allowing it to reach its storage capacity, as resource production ceases at that point. This is more of a concern at lower levels where the capacity is limited and Time to Fill is relatively short. If the player is unable to regularly collect and achieve the full potential of the collector, the Catch-Up Point is actually shorter and performing the upgrade becomes more advantageous.* The Catch-Up Point is the time at which the newly upgraded Gem Mine has equaled the total production of the mine had it not been upgraded – this does not consider recovering the cost of the Builder Elixir required to perform the upgrade.

Summary

Article Name

Gem Mine

Description

The Gem Mine can be unlocked in the Builder's Base. It requires Builder's Hall level 3 to be repaired.